Loud speaker



Patented Nov. 5, 1935 UNITED STATES 2,0zaz11 PATENT OFFICE 9 Claims.

My invention relates to loud speakers, and has to do more particularlywith the loud speakers having the cone type of diaphragm. In somerespects my improvements are applicable to the cone type of diaphragmwhether used with or without the dynamic drive, that is, the cone may bedriven either by a dynamic voice coil or a vibrating armature asordinarily employed and controlled by the voice currents.

The present application is a continuation in part of my co-pendingapplication Serial No. 670,865, filed May 13, 1933.

An object of my invention is to provide an improved and simplifiedstructure of the above character, cheap to manufacture, easy toassemble,and effective in operation.

A further object is to provide a simplified diaphragm or cone supportingframe stamped from sheet/metal in a form to carry a one-piece reshapedouter pole-piece magnet at the rear and welded thereto in a permanentand irremovable fastening.

It is also an object of my invention to provide a simplified structurein which one of two parallel leg portions of the outer-pole piece iswelded at the rear of the diaphragm support in an-initial unit assembly,a field coil is then slipped into the pole-piece and a core for thepole-piece is forcedinto the other leg portion of the polepiece in adriving fit to be supported therein and properly centered in the firstleg portion entirely by said driving fit.

One of the features of my invention resides in an improved, conesupporting frame, that is, the frame supports the cone diaphragm,resulting in a simpler and cheaper construction. This feature resides ina frustum-like' conical support or framework for carrying the conediaphragm, which framework has an inwardly extending flange forsupporting the field coil, and outwardly extending ears at the apex endof the frame for carrying the cone supporting spider and other elements.v I a I Another feature of my invention is the welded fastening of thepole-piece of the diaphragm support. This fastening not only facilitatesassembly but with these members in alignment before welding, they remainpermanently so after the operation as contrasted to other types offastening, where due to production inaccuracies in holes and thepositioning thereof, the elements are sometimes put under tension in ajig and then spring back upon removal. Qther types of fastening havebeen found to work lqose during the life of the speaker, but the weldingis permanent.

For a better understanding of my invention reference is to be had to theaccompanying drawing, in which: 5

Fig. l is a side elevation of the preferred form of my invention.

Fig. 2 is a bottom plan view of the cone supporting frame.

Fig. 3 is a top view of Fig. 2.

Fig. 4 is a left end view of Fig. 3 with part of the base broken away.

Fig. 5 is a right end view of Fig. 1 showing more particularly themethod of mounting the transformer on the cone frame; and

Fig. 6 is a modified form of cone supporting frame showing a frameadapted to take a larger size of cone than that shown in Fig. 1.

Referring now more in detail to the preferred form of construction asillustrated, I provide a suitable field magnet, the one illustratedhaving an outer U-shaped pole piece 8 enclosing a magnetizing coil 9supported upon a, central core III driven into one leg of the magnet andextending up into the other to provide the usual annular air gap intowhich the voice coil I I extends.

A cone support A is provided in which the cone I2 is supported at itsannular flange I3, the said cone carrying the voice coil I I andsupporting spider I4. This spider is of the usual thin linen reinforcedmaterial, stiff enough to act as a support, but permitting freevibration of the cone with the spider arms fastened at their ends.

Now, as to the construction of the cone frame, this is preferably in thenature of a frustrum of a cone in which the base end I3 carries the baseflange of the cone, with the apex end of the frame arranged to supportthe spider and field magnet. To this end the frame has an inwardlyextending fiange for supporting the field magnet, preferably in the formof inwardly extending ears I5 and I6 separated sufficiently to permitthe voice coil II to pass between these ears as shown in Fig. 1.

The field magnet and cone frame are preferably secured together by spotwelding the ears V I5 and I6 directly to one leg of the outer polepiece. of the field magnet.

Now as to the means for supporting the ends of the arms of the voicecoil supporting spider It, I provide a pair of outwardly extending earsH and I8 preferably formed out of the sheet metal of the side wall ofthe frame A. Thus the nds of the spider arms are fastened upon theseears by suitable studs l9 and 20 with lock nuts thereon.

By the arrangement above referred to, that is, with the flange orinwardly extending ears I 5 and I6, and the outwardly extending ears I1and I8, I provide not only a very simple and cheap construction, butalso am enabled to use the same magnetic structure and same length ofspider with different diameters of cones. For instance, in the speakerillustrated in Fig. 1, which is full size, I employ a 5-inch cone. Thisis one of the smallest sizes now ordinarily employed. Should a largercone be required, the base end 13 of the frame A is made larger, asindicated in Fig. 6, with the side or angular portion 2| of the frameextending at a more acute angle than in Fig. 1. The apex end of thecone, that is, that end carrying the ears l6 and I8, remains of the samediameter as in Fig. 1, so that although a larger cone is provided, Istill can use the same spider and magnet construction. The reverse isalso true, that is, where the larger cones are employed, and more roomis provided at the base of the frame so that a suitable spider I4 may beemployed, when a smaller cone is to be provided the same magnetstructure and spider I4 may be employed by having the spider supportingears I! on the outside of the frame and permittin the arms of the spiderto extend through the side walls of the frame to the point where theyare supported by said ears.

In connection with the outwardly extending ears, I also am enabled touse one of them for supporting the usual transformer 22 by securing amounting plate 23 to the ear [8, preferably by welding. The transformeris then attached to this plate 23 in any suitable manner, preferably bya pair of lugs 24 and 25 which are punched out of the plate 23 and arepassed up through openings in the fastening plate 26 of the transformer.

Another simplified construction which I have provided is in the methodof supporting the ends of the conductors 21 of the voice coil. For thispurpose I provide ears 28 through which an eyelet 29 is passed andinsulatingly supported by these ears through the use of a pair ofinsulating washers 30, one of which is secured against each face of theear 28 and through which the eyelet 29 is passed after which it iscurled over each washer. A voice coil conductor 21 is then passed intothe eyelet 29 and soldered thereto, after which the correspondingconductor 3| from the transformer is soldered to the outside of theeyelet 29.

In assembling the speaker, I preferably first weld one leg of the outerpole piece 8 of the field coil to the inwardly extending ears I5 and I6of the cone supporting frame. I then assemble the field coil by placingthe coil 9 over the core l0 and driving this core into the lower leg ofthe outer pole piece with the free end of the core providing an annularair gap in the other leg.

I now take the cone assembly consisting of the cone I2, voice coil IIand spider I 4, and place it in the cone supporting frame A with thevoice coil ll suitably centered in the air gap and the ends of the armsof the spider l 4 are now attached to the studs l 9 and20. The voicecoil conductors 21 are now soldered to their terminals 29 after whichthe transformer 22 is put in place and the terminals 3| thereof securedto their corresponding eyelets 29. M I claimr 1. In a loud speaker, afrustum-like one-piece conical frame stamped from a sheet of metal forsupporting a cone diaphragm, said frame having a rim and free-endedbrackets slanting inwardly therefrom and having inwardly-extending carsat their apex ends, and a field magnet ir- 5 removably mounted on saidinwardly-extending ears, and outwardly-extending ears at the apex endsstamped from the brackets themselves and extending outwardly therefromfor supporting a cone-supporting spider extending through said 10brackets.

2. In a dynamic loud speaker a cone, a voice coil unit mounted directlyon'said cone, a field magnet having a core and a bent-to-shape polepiecehaving substantially parallel side portions 15 with one side surroundingsaid core to form an annular air gap in which said voice coil operates,and a one-piece metallic cone support having an outer rim 'to which saidcone is secured, having attachment ears substantially parallel with said20 rim and permanently and irremovably secured to the face of said sideportion independently of any securing formations on the joined members,with said rim concentrically aligned with said air gap, and having anapertured wall between '35 said rim. and attachment ears,outwardly-extending ears integrally formed on said cone support nearsaid side portion, and a spider extending through the apertured wall,secured to said ears and supporting said voice coil unit accurate- 30 lyaligned in said air gap and being flexible axially of said air gap topermit said voice coil to vibrate therein.

3. In a dynamic loud speaker a cone, a voice coil unit mounted directlyon said cone, a field 35 magnet having a core and a U-shapedbent-toshape yoke having one leg surrounding said core to form anannular air gap in which said voice coil operates, and a metallic conesupport having an outer rim to which said cone is secured and 40 havingattachment ears substantially parallel with said rim and spot welded tothe face of said leg with said rim concentrically aligned with said airgap, and outwardly-extending ears integrally formed n said cone supportnear said 45 leg, and a spider supporting said voice coil unitaccurately aligned in said air gap and being flexible axially of saidair gap to permit said voice coil to vibrate therein and being securedto said ears at points outside of the contour of said 5 cone support andspaced laterally with at least one ofsaid points beyond the pole-piecewhereby the amplitude of vibration for said spider is relatively large.

4. In a dynamic loud speaker, a frustum-like 55 metal diaphragm framehaving an annular rim at its face and walls extending inwardly to theapex of the frame, a diaphragm rigidly supported in said frame on saidrim, a field electro-magnet having a one-piece outer pole-piece withsubstan- 60 tially parallel side portions lying in planes parallel tothe plane of the face of the frame, with one of said side portionspermanently and irremovably mounted at the apex of the frame, diaphragmdriving means carried centrally of 65 the diaphragm, and aligned in anopening in one of said side portions, whereby said pennanent andirremovable mounting of said outer pole-piece on the diaphragmsupporting frame maintains said frame, pole-piece and diaphragm 70driving means in permanent alignment.

5. In a dynamic loud speaker, a frustum-like metal diaphragm framehaving an annular rim at its face and attachment portions at the apexthereof, a diaphragm rigidly supported in said 75 frame on said rim, afield electro-magnet having a one-piece outer pole-piece withsubstantially parallel side portions lying in planes parallel to theplane of the face of the frame, with one of said side portions welded tothe apex of the frame, diaphragm driving means carried centrally of thediaphragm, and aligned in an opening in one of said side portions,whereby said welding fastening of said outer pole-piece on the diaphragmsupporting frame maintains said frame, pole-piece and diaphragm drivingmeans in permanent alignment.

6. A dynamic loud speaker comprising a frustum-like metal diaphragmframe having an annular rim at its face, and attachment portions at theapex thereof, a diaphragm supported on said rim in said frame, and aone-piece outer polepiece having an outside face portion and an insideleg portion, substantially parallel over their length, and said portionslying in planes parallel to the plane of the face of the frame, withsaid inside face portion of the outer pole-piece permanently andirremovably mounted at the attachment portions of the frame and retainedin permanent alignment therewith independent of any securing formationin the joined members.

7. A dynamic loud speaker comprising a onepiece sheet metal diaphragmsup-porting frame with an open face, and attachment portions at its rearend, a diaphragm supported in the frame, and a one-piece outerpole-piece having an outside face portion and an inside face portionsubstantially parallel over the length of the portions and lying inplanes parallel to the face of the frame, with said inside face portionpermanently and irremovably secured to said attachment portions tomaintain said pole-piece in permanent alignment with said frameindependent of any securing formations in the joined members.

8. A dynamic loud speaker including a diaphragm, a diaphragm support, avoice coil for operating said diaphragm and an electro-magnetic fieldmagnet including a one-piece polepiece pressed to shape having twoparallel side portions, said pole-piece mounted on said dia- 5 phragmsupport independently of any securing formations in the support and polepiece, said pole-piece having a core attachment opening in one of saidtwo side portions and a voice coil opening in the other side portion,and a one-piece core 10 extending into said core attachment opening andconfined therein with radial pressure between said side portion and saidcore, and said core being centered in said voice coil openingindependently of imperfections of parallelism between said side 15portions. 9. A dynamic loud speaker comprising an openfaced diaphragmsupporting frame having attachment portions at the rear thereof, adiaphragm supported on the frame, a one-piece outer pole- 20 piecehaving a pair of substantially parallel side portions secured at oneside portion at the rear of said frame in a permanent and irremovablemanner to maintain said frame and pole-piece in permanent alignment,said pole-piece having an 25 opening in each side portion, a core ofmagnetic material retained in one of said openings by a driving-fitbetween the end of said core and the inside surface of the opening, withthe other end of said core extending into the other of said openings toprovide an annular air gap, a voice coil in the air gap to drive saiddiaphragm, with said pole-piece and frame assembly, and polepiece andcore assembly maintained in permanent alignment by the manner in whichsaid elements are secured together to cause all of said elements toremain in permanent alignment with respect to one another.

JAMES P. QUAM.

